The invention provides a class of substituted quinazolinone compounds and methods of treating diseases mediated by PI3K.delta. activity. The disclosed compounds are useful in treating diseases such as bone-resorption disorders; and cancer, especially hematopoietic cancers, lymphomas, multiple myelomas and leukemia. The compounds are also useful in disrupting or inhibiting cellular processes such as leukocyte function or accumulation, neutrophils function, lymphocyte proliferation, and endogenous immune responses.

Claim:

What is claimed is:

1. A compound of the formula: ##STR00183## .[.(S)-5-fluoro-3-phenyl-2-[1-(9H-purin-6-ylamino)-propyl]-3H-quinazolin-- 4-one,.]. or a pharmaceutically acceptable saltthereof.

2. A pharmaceutical composition comprising a compound according to claim 1 and at least one pharmaceutically acceptable excipient.